a) a cigar because one end burns like the fuse on a cannon
b) a blunt (cigar filled with weed) because after you smoke it you're head is going to explode.
c) any form of firework
d) a penis, cause after you suck it, it explodes in your face
e) a person, because they could blow you to bits in some way (pwn you)
f) the muscles (usually arm) of a person, because cannons are just bigger guns
g) a firearm, preferablly the one you use to kill the person using this ambigous word in front of you. Don't use this word, people will have no clue what you're talking about.